This invention relates generally to free wheeling devices. and more particularly to a free wheel clutch mechanism useful with crank operated exercise bicycles employing an inertia flywheel.
The benefit of exercising on a direct drive exercise bicycle is well known. Direct drive exercise bicycles typically utilize a high-inertia flywheel driven by a fixed-gear drive train. The flywheel is driven by the rider up to relatively high revolutions per minute (rpm). Because of the direct drive feature, the drive train must rotate at a fixed ratio of rpm as compared to the flywheel based on the gear ratio. One benefit of the direct drive exercise bicycle is that the direct drive gear train provides xe2x80x9cpedal-through assistancexe2x80x9d for the rider. The xe2x80x9cpedal-throughxe2x80x9d feature assists the rider by pushing the pedal through the top and bottom dead center pedal positions to help make the transition smooth and efficient. Other benefits are derived from the direct drive interaction between the inertia flywheel and the crank arms to which the rider""s feet are attached. The inertia flywheel provides a smooth, non-jerky pedaling rhythm which provides an efficient and rigorous exercise for the rider, especially at relatively high rpms, such as 60 to 100 rpm.
In the application of this invention to an inertia flywheel exercise bicycle, positive drive is required to rotate the inertia wheel in order to overcome regulated retardation torque applied by brake means used to provide resistance against which the rider/operator works. The inertia wheel provides means for continued drive train (wheel to crank to leg) movements during those periods when the crank is in top dead center or bottom dead center positions, where the rider""s legs are somewhat weaker in providing rotary motion to the activating crank arms. The flywheel affords smooth and steady operation for the rider.
The direct drive relationship between the flywheel and the drive train is also a drawback of exercising on this type of bicycle. The direct drive relationship is inconvenient when the rider wishes to quickly stop the pedals, or loses the pedaling rhythm required to keep up with the rotating flywheel. In the usual flywheel exerciser employing such a direct drive relationship, it is necessary for the rider/operator to gradually decrease his cranking rate in order to slow down the inertia wheel. The rider cannot suddenly stop pedaling inasmuch as the inertia flywheel continues to drive the crank arms.
Of similar importance is the desirability of providing pedal assist to the rider/operator""s legs when cranking at a speed slower than that necessary to positively drive the flywheel, and providing for a gradual reengagement and lockup between the pedal actuated drive shaft and the free wheeling flywheel in order to avoid abrupt impact when reengaging the moving flywheel.
It is with these issues in mind that the present invention was developed.
The present invention in general terms concerns a clutch mechanism for use on an exercise bicycle, and consequently, the present invention recognizes that it is desirable to have a free wheeling mechanism for an exerciser of the inertia flywheel type which provides means for selectively disengaging the flywheel from the drive means. The clutch mechanism allows for the beneficial direct-drive connection between the drive train and the flywheel, and also allows the drive train and flywheel to move independently from one another, or xe2x80x9cbreak freexe2x80x9d, when a sufficient force is applied to the drive train or the flywheel.
In general, the invention is an exercise bicycle including a frame having a seat and handlebars, a high-inertia flywheel having a hub at a center of rotation, the flywheel being rotatably supported on the frame at the hub, and a drive train including a drive sprocket, a crank arm attached to and extending from the drive sprocket, and a pedal attached to the crank arm, the drive train being rotatably supported by the frame. The drive train also includes a slave sprocket fixed to the flywheel at the hub, with the drive and slave sprockets connected in a direct-drive relationship, the drive train driveable in a forward and rearward directions to cause the flywheel to rotate. A clutch mechanism is positioned in engagement with the slave sprocket and the hub to create a frictional engagement between the sprocket and the hub, and to establish a break-free force. When the drive train is actuated in the forward direction, the slave sprocket and the hub move together under a mechanical engagement, and when the drive train is actuated in the rearward direction under the influence of a force greater than the break-free force, the clutch mechanism slips between the slave sprocket and the hub, allowing the slave sprocket and the flywheel to move independently of one another. There is no mechanical engagement between the sprocket and the hub in the rearward direction as there is in the forward direction, established by the one-way bearing.
More specifically, the slave sprocket defines a sprocket collar mounted on the hub and also includes an engagement collar. A one-way bearing is mounted between the sprocket collar and the hub to allow the sprocket collar to drive the hub when the sprocket collar is driven in a forward direction, and to allow the sprocket collar to spin independently of the hub when the sprocket collar is driven in the rearward direction. An engagement flange fixedly mounted on the hub corresponds to the engagement collar, and compression means are mounted on the flywheel to bias the flange and the collar towards one another. A clutch material member is positioned between the engagement flange and the collar, and is clamped therebetween by the compression means to cause the engagement flange to move in conjunction with the sprocket collar. The engagement creates a break-free force required to cause the sprocket collar to move independently of the engagement flange. When the drive train is actuated in the forward direction, the sprocket collar and the engagement flange move together, and when the drive train is actuated in the rearward direction and overcomes the break-free force, the engagement flange slips with respect to the collar, allowing the sprocket collar and the flywheel to move independently of one another.
In another embodiment, the slave sprocket defines a sprocket collar mounted on the hub and defines an inner and outer engagement collars. A one-way bearing is mounted between the sprocket collar and the hub to allow the sprocket collar to drive the hub when the sprocket collar is driven in a forward direction, and to allow the sprocket collar to spin freely on the hub when the sprocket collar is driven in the rearward direction. An inner engagement flange is fixedly mounted on the hub corresponding to the inner engagement collar, and an outer engagement flange is fixedly mounted on the hub corresponding to the outer engagement collar. Compression means are mounted on the flywheel to bias the inner flange and the inner collar towards one another, and to bias the outer flange and the outer collar towards one another. A clutch material member is positioned between the outer engagement flange and the outer collar, and between the inner engagement flange and the inner collar, and clamped therebetween by the compression means to cause the inner and outer engagement flanges to move in conjunction with the sprocket collar. The engagement creates a break-free force required to cause the sprocket collar to move independently of inner and outer engagement flanges. When the drive train is actuated in the forward direction, the sprocket collar and the inner and outer flanges move together, and when the drive train is actuated in the rearward direction and overcomes the break-free force, the inner and outer engagement flanges slip with respect to the inner and outer collars, allowing the sprocket collar and the flywheel to move independently of one another. There are other embodiments of the invention disclosed which perform the same function with very similar structure.
Also, the invention includes an exercise bicycle frame for use with the clutch mechanism. The frame includes a front support, a rear support, and a brace member extending between the front and rear ground supports. In addition, front forks are included that have a top end and a bottom end, and are attached at the bottom end to the front ground support. The front forks rotatably support a high-inertia flywheel. A rear post is included that has a top member and a bottom member, the top member attaching to the bottom member in a rear offset overlapping manner, the rear post defining a top end and a bottom end. The rear post is attached at the bottom end to the brace member. An articulated beam is attached to and extends from the top end of the front forks downwardly and rearwardly to a midpoint between the front forks and the rear post, then extends horizontally to the rear post at the intersection of the top and bottom members of the rear post. A rear truss extends from the top member of the rear post to the rear support. A handlebar is attached at the top end of the front forks, and a seat is attached at the top end of the rear post. A front area is defined by the front forks, articulated beam, rear post and brace member forming a five-sided polygon, and a rear area is defined by the rear post, rear truss, and brace member forming a five-sided polygon.
Accordingly, it is a primary object of the present invention to provide a free-wheeling clutch mechanism that allows an exercise bike to include the direct-drive relationship between the drive train and the flywheel, and at the same time allow the drive train and the flywheel to turn independently from one another under certain conditions.
Other aspects, features and details of the present invention can be more completely understood by reference to the following detailed description in conjunction with the drawings, and from the appended claims.